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Texas Instruments LM2678T-12
- Part No.:
- LM2678T-12
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-7 Formed Leads
- Datasheet:
-
LM2678T-12.pdf
- Description:
- IC REG BUCK 12V 5A TO220-7
- Quantity:
- Payment:
- Shipping:
Inventory:4,583
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Product details
Overview
LM2678T-12 from Texas Instruments is a monolithic step-down (buck) DC-DC switching regulator with fixed 12 V output, 5 A load capability, 8–40 V input range, 260 kHz fixed-frequency oscillator, and ±2% output voltage tolerance over full line/load/temperature. It integrates a 120 mΩ DMOS high-side switch and supports ON/OFF control for low-power standby.
For engineers reviewing the LM2678T-12 datasheet, LM2678T-12 pinout, LM2678T-12 application, or LM2678T-12 equivalent, key selection considerations include its 92% peak efficiency at 24 VIN/5 A, thermal shutdown protection, 50 µA shutdown quiescent current, and compatibility with standard off-the-shelf inductors and Schottky diodes in TO-263-7 (KTW) package.
Technical Context
The LM2678T-12 implements a voltage-mode PWM controller with internal 260 kHz oscillator and integrated 120 mΩ DMOS high-side power switch. Its feedback loop uses a precision 1.21 V reference and high-gain amplifier to regulate output via direct connection of FB pin to VOUT (no external divider required for fixed 12 V version).
It operates in continuous conduction mode up to 5 A, features cycle-by-cycle current limiting (6.1–8.3 A), thermal shutdown, and an ON/OFF pin with 1.4 V threshold and 20 µA pull-up. Standby mode reduces quiescent current to 50 µA while maintaining fast wake-up response.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12 V, ±2% tolerance over –40°C to 125°C junction temperature, 15–40 V input, 100 mA–5 A load. |
| Max Output Current | 5 A continuous; current limit set internally at 6.1–8.3 A depending on temperature. |
| Input Voltage Range | 8 V to 40 V DC; absolute maximum 45 V; supports wide industrial and battery-derived supplies. |
| Switching Frequency | 260 kHz fixed (±11% tolerance); enables use of compact magnetics and reduces EMI compared to lower frequencies. |
| Efficiency | Up to 92% at VIN = 24 V, IOUT = 5 A; enabled by low RDS(ON) (0.12 Ω typ) DMOS switch. |
| Quiescent Current | 6 mA typical in active operation; drops to 50 µA in shutdown (ON/OFF pin < 0.8 V). |
| Thermal Protection | Integrated thermal shutdown with automatic recovery; junction temperature limit 125°C. |
Pinout & Package
LM2678T-12 is supplied in the KTW (TO-263-7) thermally enhanced surface-mount package (10.1 mm × 15.24 mm), with exposed DAP connected to GND for optimal heat dissipation. Pin 1 is Switch_output, Pin 2 is Input, Pin 3 is CB (bootstrap capacitor), Pin 4 is GND, Pin 5 is NC, Pin 6 is FB, and Pin 7 is ON/OFF.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Switch_output) | High-side DMOS drain node | Switching node connecting to inductor and cathode of external Schottky diode; swings between VIN and ~–0.5 V during OFF time. |
| 2 (Input) | Main power supply input | Connects to 8–40 V source and input bypass capacitor; path to GND must be short to minimize switching noise and voltage spikes. |
| 3 (CB) | Bootstrap capacitor terminal | Connects 100 nF ceramic capacitor to Switch_output to generate gate drive voltage > VIN for full enhancement of internal DMOS switch. |
| 4 (GND) | Power ground reference | Primary return path for input/output capacitors, thermal pad (DAP), and internal circuitry; requires low-inductance PCB ground plane. |
| 5 (NC) | No-connect | Internally unconnected; must remain floating-no external connection permitted. |
| 6 (FB) | Feedback sense input | Direct connection to 12 V output (no resistor divider); internal 1.21 V reference compares against this node to maintain regulation. |
| 7 (ON/OFF) | Enable/disable control input | Logic-level input: ≥1.4 V enables regulation; ≤0.8 V forces shutdown with 50 µA IQ; internal 20 µA pull-up allows floating for always-on operation. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120 mΩ DMOS switch | Enables high-efficiency 5 A buck conversion without external MOSFET, reducing BOM count and layout complexity. |
| Fixed 12 V output with ±2% tolerance | Eliminates need for external feedback resistors; ensures stable, production-ready output across temperature and load. |
| 260 kHz fixed-frequency PWM | Provides predictable EMI profile and simplifies filter design; supports use of standardized, low-cost inductors. |
| 50 µA shutdown quiescent current | Permits ultra-low-power system sleep modes while retaining fast wake-up (<100 µs typical) and no external bias circuitry. |
| Built-in thermal shutdown & current limit | Protects device under overload or poor heatsinking; auto-recovery avoids latch-up and enables robust field operation. |
Applications
| Industrial Power Supply | Battery-Powered Equipment |
|---|---|
Use Scenario: 24 V industrial bus converted to regulated 12 V for PLC I/O modules, sensors, and actuators. IC Role / Device Role / Timing Role: Primary step-down regulator delivering 5 A continuous power with high line/load regulation and thermal resilience. Use Value: Maintains ±2% output accuracy across 8–40 V input transients and –40°C to 85°C ambient, eliminating need for post-regulation LDOs. | Use Scenario: 28 V LiFePO₄ battery pack powering 12 V motor drivers and microcontrollers in portable test equipment. IC Role / Device Role / Timing Role: High-efficiency preregulator enabling long runtime and minimal thermal rise in enclosed enclosures. Use Value: 92% peak efficiency at 24 VIN/5 A extends battery life; 50 µA shutdown current preserves charge during idle periods. |
| Automotive Aftermarket Systems | Telecom Line Card Power |
Use Scenario: 12–36 V automotive battery input supplying stable 12 V to infotainment head units and camera modules. IC Role / Device Role / Timing Role: Robust buck converter handling cold-crank (6.5 V) and load-dump (40 V) conditions with built-in protection. Use Value: Wide 8–40 V input range and thermal shutdown ensure reliable operation across automotive voltage extremes. | Use Scenario: Central office power shelf distributing 12 V to multiple line cards requiring clean, well-regulated supply. IC Role / Device Role / Timing Role: High-current local point-of-load regulator replacing less efficient linear solutions. Use Value: TO-263-7 package with exposed DAP enables >35°C/W thermal performance on 1 oz. copper, supporting dense board layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596T-12 | 3 A max output, 150 kHz switching frequency, higher RDS(ON) (0.16 Ω), no ON/OFF pin. | Suitable for lower-current designs where size and efficiency are secondary to cost. | Select LM2596T-12 only if 3 A output suffices and 260 kHz EMI profile is not required. |
| TPS54560B | 5 A, 100 V input, adjustable output, 2.5–600 kHz programmable frequency, integrated soft-start. | Preferred for high-input-voltage or programmable-output systems needing advanced protection and sequencing. | Choose TPS54560B when input exceeds 40 V or when design flexibility (adjustable VOUT, frequency tuning) outweighs fixed-12V simplicity. |
Compared with LM2678T-12, LM2596T-12 offers lower cost but reduced current and efficiency, while TPS54560B provides wider input range and configurability at the expense of added external components and design complexity for fixed 12 V use.
Availability
LM2678T-12 is available at Aetrix Electronics and suitable for industrial power supplies, battery-powered instrumentation, and automotive aftermarket electronics requiring stable component supply, long-term lifecycle support, and consistent parametric performance.
Supply support for LM2678T-12 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management ICs, with decades of expertise in high-reliability power conversion solutions.
The LM2678 series belongs to TI's SIMPLE SWITCHER® family-designed for rapid, robust DC-DC buck regulator implementation using minimal external components and industry-standard magnetics.
FAQ
What is the maximum input voltage rating for LM2678T-12?
The absolute maximum input voltage for LM2678T-12 is 45 V DC. However, the recommended operating range is 8 V to 40 V. Operation above 40 V risks exceeding safe operating area limits and may trigger overvoltage protection or cause permanent damage. Designs should include input transient suppression if exposed to automotive load-dump events.
Does LM2678T-12 require an external feedback resistor network?
No, LM2678T-12 does not require external feedback resistors. As a fixed 12 V output variant, it uses internal precision resistors to set the feedback reference. The FB pin must be connected directly to the output capacitor's positive terminal to enable regulation-no external divider is needed or supported.
What thermal performance can be expected from LM2678T-12 in TO-263-7 package?
In the KTW (TO-263-7) package with proper PCB copper area (≥0.4896 in² of 1 oz. copper), LM2678T-12 achieves a junction-to-ambient thermal resistance (RθJA) of 35°C/W. With 12 vias to an inner ground plane, this improves to 26°C/W-enabling full 5 A operation at up to 85°C ambient without forced airflow.
Can LM2678T-12 be synchronized to an external clock?
No, LM2678T-12 cannot be synchronized to an external clock. It uses an internal fixed-frequency 260 kHz oscillator with ±11% tolerance. There is no SYNC pin or frequency-adjust capability-making it unsuitable for noise-sensitive applications requiring clock synchronization across multiple rails.
Is LM2678T-12 RoHS-compliant and halogen-free?
Yes, LM2678T-12 is RoHS-compliant and halogen-free per Texas Instruments' published environmental compliance documentation (SLMA001). It meets JEDEC J-STD-609 Category 1 for bromine/chlorine content and is qualified for lead-free solder reflow per J-STD-020.
LM2678T-12 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-220-7 Formed Leads
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 15V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 12V
- Voltage - Output (Max):
- -
- Current - Output:
- 5A
- Frequency - Switching:
- 260kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-7
LM2678T-12 FAQ
1.How can I place an order for LM2678T-12 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678T-12 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM2678T-12 reliable?
The price and inventory of LM2678T-12 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2678T-12 is usually 5 days.
3.What payment methods are accepted for LM2678T-12?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678T-12 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678T-12?
LM2678T-12 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678T-12 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM2678T-12?
For technical support, including LM2678T-12 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678T-12 requirements.
6.How does Aetrix verify that LM2678T-12 is sourced from the original manufacturer or authorized distributors?
All LM2678T-12 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM2678T-12 meets industry standards.
7.What is the process for return or replacement of LM2678T-12?
All LM2678T-12 units undergo pre-shipment inspection (PSI). If there is an issue with LM2678T-12, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM2678T-12 part is unused and in its original packaging.
Return procedure for LM2678T-12:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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